DescentBB

Router: Linksys WRT54G Version 6
FirmWare: DD-WRT v23 SP2
Internet Speed: 2megabits DOWN/ 512 Kilobits UP
Number of PC's on LAN: 5

Intent: Want to know the best Quality of Service setup if one wants the LAN to have ability to download at say 60-100KB/S, play online games, and use VoIP service.

Also, if there are any other firmwares that may handle QoS better than DD-WRT for my router. (Tomato won't work cause of the version I believe)

Maximize throughput for downloading; minimize delay for real-time online games; maximize reliability for VoIP.

Somehow I doubt if it will actually matter. You can always experiment...

It can be done, but requires more than your standard router can handle, perhaps you should consider using an old Pentium3 class computer with dual LAN cards and a router build of OpenBSD. Just use the linksys for the wireless.

yeah either OpenBSD or Smoothwall

you can do that with the firmware you have on your router, just give VOIP premium service.